Effect of temperature on the extraction of Pd by liquid tin from molten borosilicate glass containing simulated radwaste

• Published in: Journal of non-crystalline solids 2011-07, Vol.357 (15), p.2911-2919
• Main Authors: Jena, Hrudananda, Kutty, K.V. Govindan, Rao, P.R. Vasudeva
• Format: Article
• Language: English
• Subjects: Applied sciences; Borosilicate glasses; Entrainment; Entrainment of Pd in glass melt; Exact sciences and technology; Extraction; Extraction of Pd from borosilicate glass; Glass; Heat treatment; Palladium; Pd-rose; Pollution; Radioactive wastes; Separation; Tin; Wastes; XRD
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2011.03.033

Separation of Pd from borosilicate glass-melt containing simulated high level radioactive waste (Pd, Mo, Cs, Sr, Zr, Nd, Ni, Fe) using Sn as the solvent metal was studied on lab scale. The separation of Pd was studied using varying amounts of Sn, and the percentage of extraction of Pd and other elements was investigated by varying the process temperature and the starting material for Pd. The process temperature was observed to have a profound influence on the separation of Pd from the glass melt to the metallic tin phase. The % extraction of Pd was found to be less for the batches heat-treated at temperatures below 900°C. The decrease in the % extraction was due to the entrainment of Pd in the glass phase for the samples heat-treated at low temperatures. The entrainment of Pd leads to the formation of Pd-rose like structures in the glass phase as observed by SEM and EDAX. Similarly, Mo, Fe and Na also formed separate phases inside glass matrix when the samples were heated below 900°C. However, entrainment was not seen when the samples were heat-treated above 1050°C in Ar. At 1200°C, a recovery of about 99% of Pd was obtained. The formation of a PdSn4 type intermetallic phase was noticed in tin metallic phase. The extraction behavior of Pd in borosilicate glass melt was also studied by using Pd(NO3)2 instead of Pd powder as staring material, and the results showed that the process temperature is the key determinant of the extraction behavior of Pd. ► Removal of Pd using Sn from borosilicate glass melts containing simulated radwaste. ► Temperature has pronounced influence on the % extaraction of Pd. ► Pd entrainment can be avoided by increasing the vitrification temperature to 1150°C. ► The % extraction does not get affected by varying the amount of Sn in each batch. ► PdSn4 intermetallic phase was identified by XRD in the Sn- metal button phase.